This application claims the priority of German Appln. No. 19709415.5-13, filed Mar. 7, 1997, the disclosure of which is expressly incorporated by reference herein.
This invention concerns a particular closure for a filling tube of the tank of a motor vehicle.
A closure of this kind is known from German patent publication DE 19,504,265 A1. The closure described in this publication includes a closure cover which can be swiveled around a swivel axis. This swivel axis extends perpendicularly in relation to a plane including the filling tube axis. An open position is obtained when the closure cover is swiveled down in the filling direction. In a closed position, the closure cover lies at the opening edge of the filling tube, sealing the tank inner space from the side. The swivel arrangement connected to the closure cover includes a lever. The lever is attached to a wall of the tank inner space so that it can be swiveled around the swivel axis. This axis extends through a slit from the outside into the filling tube. The lever is arranged such that it can be operated by the filling pipe of a nozzle. A torsional leg spring is arranged around the swivel axis and is supported by both the lever and a wall projection of the inner space of the tank. The lever extends in a direction opposite to that of insertion movement of the nozzle. The leg spring generates an opposing force during insertion of the nozzle. The lever is also connected at the bottom, by a joint, to a tip lever by handles. At one end, the lever has its swivel axis attached to the wall of the tank inner space. On the other end, the lever carries the closure cover.
When the lever is operated, the transmission rate between the lever and the tip lever is reduced as the open position enlarges so that relatively large swivel paths of the closure cover can be obtained with short shifting paths of the filling pipe. In connection with the leg spring, this allows a modified closing force for the closure cover which depends upon the shifting path of the filling pipe. As a result, the closure force is greatest when the cover is closed.
One disadvantage of this construction is that, in an insertion phase, when pushing open the closure cover, the greatest force has to be exerted. This is particularly inconvenient during manual refuelling. Sealing problems also occur in the slit through which the lever extends. The operating mechanism of the closure cover also requires a number of mechanical parts (shafts, levers, and handles). The operating mechanism, therefore, is expensive and quite complicated to assemble.
It is a primary object of the invention to develop a closure of the kind described above which provides an improved operation of the closure cover for refuelling. This operation requires application of the least amount of force possible on the total insertion path beyond the filling pipe while, at the same time, providing a safe and reliable closure which functions in a simple manner.
This object is attained by a particularly constructed closure for a filling tube of a fuel tank for a motor vehicle. A swivel closure cover is arranged outside of a center opening of the filling tube in the tank and is displaceable about a swivel axis positioned perpendicular to the center axis of the opening. A spring prestresses the cover in a direction against insertion movement of a filling pipe of a nozzle and into contact with a lower surrounding opening edge of the opening in a closed position to form a seal. A swivel facilitating structure that can be contacted by the filling pipe is arranged on the closure cover to assure that the closure cover is swiveled in a forcesaving manner. The swivel facilitating structure is provided on an upper side of the closure cover, is shaped as a curved disc, and has a guidance plane facing the swivel axis. The guidance plane has a highest geodetic position which, in the closed position, forms an end region of its course that extends in the direction of the swivel axis. The end region is arranged so as to oppose the swivel axis of the closure cover close to its edge. When the cover is in the closed position, the swivel axis lies opposite an end section, farthest from the swivel axis, which initially engages a front side of the filling pipe during an insertion phase.
A structure by which the closure cover is operated is provided directly on the closure cover at the farthest possible location from the swivel axis. As it is inserted, a filling pipe first comes into contact with this closure cover structure. A maximum lever arm for operation results, so that only a very small force must be exerted to swivel the closure cover from its closed position. By inserting the filling pipe further, the closure cover passes through various swivel positions and different insertion depths. The filling pipe moves into a guidance surface or "plane" on the cover structure and continues to move along this surface during the insertion movement. Initially, the filling pipe starts at an end region of the closure cover farthest from the swivel axis. The lever length is thereby reduced, but the lever effect associated therewith continues to increase. The amount of force needed for opening the closure cover, therefore, is kept as small as possible. At the same time, the area of the filling pipe closest to the swivel axis approaches the closure cover, so that the area of the guidance plane farthest away from the swivel axis lifts off from a certain insertion depth. The lever effect is transferred to the area lying on the guidance plane closest to the swivel axis. In this way, the lever effect is abruptly reduced, due to the relatively small lever length, and the amount of force needed suddenly becomes greater. The lever arm, however, becomes longer during the subsequent insertion movements of the filling pipe, so that the area neighboring the end region farthest from the swivel axis is guided toward the guidance plane. At the same time, a wedge effect provided by the inserted filling pipe supports the opening, so that the corresponding amount of direct impact force needed for inserting the filling pipe or for swiveling the closure cover connected thereto is reduced considerably. In this way, the opening of the closure cover is reached in the installation of the end region farthest from the swivel axis on the side (cylinder jacket) of the filling pipe. The expensive lever mechanism previously required can be eliminated. Construction space is saved, and the number of components is reduced as well. At the same time, assembly of the closure is simplified, and simple retrofitting with swiveling elements according to the invention is always possible. Such a retrofitting can start from a conventional construction without the force-saving swiveling structure of the invention.
Furthermore, by eliminating the plurality of parts, and by placing the swiveling structure within the opening without constructive penetration of the opening wall by an operating lever, sealing problems resulting from such penetration are eliminated. A pre-stressed closure spring can be used to exert a relatively high closing force due to the high lever effect. A safe and reliable closure is achieved, and a particularly good seal is obtained by the pressure the closure cover exerts against the edge of the opening because of the spring force. The high incidence of flaws in the hermetic closure that formerly resulted from the plurality of parts is eliminated. Improved reliability and a safer and longer service life are provided to the motor vehicle as a result.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.